1. Technical Field
This invention generally relates to a device used to aspirate a gastro-intestinal tract and/or to deliver nutrients, fluids, medication, and/or aspirate into the gastro-intestinal tract. The invention specifically relates to devices and methods for safely, efficiently, and continuously aspirating from and feeding into the gastrointestinal tract.
2. Background Art
Frequently, hospital patients are unable to consume food normally. In these situations, it is often necessary to use a feeding tube to provide nutrition, fluids, and/or medicine. Such a tube is inserted into a patient's gastro-intestinal tract through the nose (nasogastric or nasoenteric tubes) or surgically by means of a gastrostomy or jejunostomy. Because adequate nutritional intake facilitates recovery, the proper use of a feeding tube and an associated device for feeding through the feeding tube can greatly benefit a patient.
However, the feeding tubes and the associated devices and methods also pose some discomfort, and even some potential risks, to patients. A number of commercially available feeding tubes exist. Unfortunately, all presently available feeding tube devices and methods for feeding through the tubes suffer from a variety of deficiencies. One common problem is that a feeding tube may deliver the fluids (which include liquid nutrition, hydrating fluids, and medicine to the patient) at a rate exceeding the ability of the gastro-intestinal tract to absorb such fluids. This results in an accumulation of fluid within the intestine. In particularly bad cases, accumulation of fluid causes distension of the intestine that leads to the temporary loss of all residual intestinal function. In rare cases, this intestinal distention may induce fatal vagal reflex circulatory changes. Approximately 1 in 1000 patients that are fed through a jejunal tube die of bowel necrosis, a complication that may be related to the lack of safety of the devices and methods of feeding directly into the gastrointestinal tract. Severely ill, malnourished patients are most at risk for developing complications associated with overfeeding. Aside from being at high risk, these patients are also most in need of the earliest optimum nutrition. In any case, when a patient's intestine is not operating fully, then the amount of nutrition the patient can receive is limited. However, adequate nutrition is obviously a critical part of anyone's health and is necessary in order to provide optimum recovery for a patient. It is thus desirable to deliver as much nutrition to a patient as can be absorbed safely by the patient's impaired gastro-intestinal tract. Devices and methods of the past are deficient in providing this maximum feeding in a safe, prompt, and effective way to patients in need.
It is not desirable to simply deliver a maximum amount of nutrition into a patient's intestine. The reason for this is that overfeeding, which is delivering feedings at a rate exceeding the ability of the patient's gastrointestinal tract to absorb its own secretions plus the added nutrition, itself presents serious hazards to a patient. Overfeeding a patient leads to an accumulation of fluid, which distends the intestine. This intestinal distension can lead to fatal circulatory changes. More commonly, complications from overfeeding include the temporary further impairment of intestinal function, with nausea and vomiting, which at a minimum causes discomfort and delays recovery. A common and more severe related complication is impaired ability to breathe deeply and cough because of abdominal distention, resulting in atelectasis and pneumonia.
A patient's impaired digestive system may also produce too many digestive secretions for the patient to reabsorb immediately. A typical person secretes seven to eight liters of fluid per day, starting with saliva. All secretions normally are reabsorbed by the intestine, without net loss or gain of fluid for the body. Unfortunately, during recovery from surgery the level of secretions remains relatively constant or decreases, while the intestine's ability to absorb secretions is typically impaired, sometimes severely. The result can be a build up of fluid in the intestine, with the same detrimental side effects as found with over-feeding. The problem of digestive secretions can be exacerbated by feeding.
When concentrated nutrition is delivered to a patient's gastro-intestinal tract, the body's natural response is to produce digestive secretions to dilute the feedings and break down the complex nutrients for absorption by the intestine. However, if a patient's gastro-intestinal function is severely impaired only a portion of the total fluid may be absorbed. By way of example, for 2 ml of nutrition delivered to the gastro-intestinal tract, 10 ml of digestive secretions may be provided in response. The intestine may temporarily be capable of absorbing only 2 ml of fluid, resulting in a net increase of 10 ml to the volume of fluid in the gastro-intestinal tract. Thus, nutrition delivered to the intestine may be competing with digestive secretions for absorption by the intestine. This problem may worsen as feedings continue, causing progressive intestinal distension which, in turn, further impairs intestinal function and reduces the amount of nutrient actually being absorbed. To avoid problems of overfeeding or excessive secretion build up during recovery, a patient's gastrointestinal tract may be aspirated to remove excessive fluid. However, any secretions removed in this way will cause a net loss of fluids and dehydration of the patient. Past solutions to this problem include providing replacement fluids in the form of an intravenous saline solution. However, this method of fluid replacement does not conserve nutrients and digestive juices that may have otherwise been used.
Another problem that has not adequately been solved is that the very presence of a nasal feeding tube stimulates swallowing by the patient, introducing additional air into the intestine. The presence of air within the gastro-intestinal tract interferes with the propulsion and absorption of nutrition and can be quite uncomfortable or painful to a patient. The use of an aspirating tube to remove air from the gastro-intestinal tract has been used to combat this problem. As set forth above, aspirating introduces additional problems of increased risks of dehydration and removal of potentially beneficial nutrients.
Unfortunately, the use of a second tube for aspiration presents new problems. The introduction of a second tube only adds to the pain and discomfort experienced by a patient. Furthermore, if a separate second tube is used, it may be difficult to effectively locate it proximate to the feeding tube, thereby preventing it from aspirating excessive food present in the gastro-intestinal tract.